swust oj 1075: 求最小生成树(Prim算法）

#include <iostream> 
using namespace std;

typedef struct
{
	int n;
	int e;
	char data[500];
	int edge[500][500];
}Graph;

typedef struct
{
	int index;
	int cost;
}mincost;

typedef struct
{
	int x;//起点
	int y;//终点
	int weight;//权重
}EDGE;


typedef struct
{
	int index;
	int flag;
}F;

void create(Graph& G, int n, int e)
{
	int i, j, k, w;
	char a, b;
	for (i = 0; i < n; i++)
		cin >> G.data[i];
	for (i = 0; i < n; i++)
		for (j = 0; j < n; j++)
		{
			if (i == j)
				G.edge[i][j] = 0;
			else
				G.edge[i][j] = 100;
		}

	for (k = 0; k < e; k++)
	{
		cin >> a;
		cin >> b;
		cin >> w;
		for (i = 0